To control the rotational speed of motors, for example, electric motors or internal combustion engines, PI controllers may be used, which include various parameter sets having parameters (proportional coefficient and integral coefficient) for the PI controller for various operating states. Furthermore, it is possible to enhance PI controllers with a differential component to form a PID controller.
The largest disturbing variable in a rotational speed control loop is the load coupled to the motor, which, during operation, may vary over a large range of values within a short time, for example, due to the connection of loads of a motor vehicle such as an air conditioner or power steering, or due to changing driving resistances when coasting.
In order to avoid steady-state control deviations, the speed controller includes an integrating I-component which compensates for the deviations in the load. The integrating I-component is determined as a function of the control deviation. However, because of the integration, this results in a larger phase delay which makes a phase-gaining differentiating D-component of the speed controller necessary.
Therefore, there is a need for a better way to achieve a control quality than that of previous PI(D) controllers.